Usually it's something small like a glove or a cell phone.
But now, an artist is trying to figure out what happened to two of his valuable paintings he left in a taxi.
Renelio Marin took a yellow cab to his Upper East Side apartment last week after showing his work at a café in Harlem.
But he'd left two of his most important pieces inside the cab.
He found his cab receipt but couldn't track down the paintings.
The paintings depict breakdancers and are valued at between $2,000 and $2,500 each.
Marin is working with the Taxi and Limousine commission to track down the paintings.
If any one finds the missing paintings they're asked to drop them off at one of the TLC's designated lost property police precincts.
Designated Lost Property Police Precincts
167 E. 51st Street
Central Park Precinct
86th Street & Tranverse Road
191 Union Street
100 Meserole Avenue
107th Precinct 71-01 Parsons Blvd
92-15 Northern Blvd
900 Fteley Avenue
78 Richmond Terrace